1. Field of the Invention
The invention is in the field of airborne substance detectors.
2. Description of the Related Art
Increased concern about terrorism has brought to the fore the need to screen personnel entering public areas and other sensitive spaces where attacks might occur. Screening people for chemicals, such as traces of explosives, is a time-consuming process, making it impractical to be applied for screening large numbers of people rapidly. In addition, current screening methods generally provide notice to those screened of the occurrence of screening. It would be desirable to have screening that was discrete, cost-effective, did not unduly slow movement of people, and successful in finding the desired substances (which may include contraband such as illegal drugs).